In the racks of fine datacenters:

Hacs (ahem)

These are self-built systems built for OS X but aren’t Macs. They’re fickle and bitchy like a Blue & White G3. I often tell people that having a Hacintosh is a lot like flying the Millennium Falcon — they’re fast hunks of junk that require frequent tune-ups and a completely different set of limitations and restrictions from Apple’s hardware. My Hacintoshing probably needs some better documentation because hobbyist computing is more on the fringe than it has ever been.